Ref. [1]} can be consulted for a discussion of the \(D^*\)  decay rate and the strong interaction corrections to (REF ).
 The decay \({\mathbf {D^{*+} \rightarrow \pi ^0 D^+}}\) .
From the hamiltonian (REF ) and Eq. (REF ), the relevant term in the hamiltonian is
\({\cal H}_I^\pi =\frac{g}{\sqrt{2}f_\pi }\, {\mathbf {q \cdot \sigma _u}}\) 
